Knee-control mechanism for electric sewing machines



D.H.CHASON Fhb.20,l934.

KNEE CONTROL MECHANISM FOR ELECTRIC SEWING MACHINES 3 Sheets-Sheet 1Filed June 25, 1932 Witness:

D. H. CHASON 1,947,827 KNEE CONTROL MECHANISM FOR ELECTRIC SEWINGMACHINES Feb. 20, 1934.

Filed June 25, 1932 3 wSheets-Sheet. 2

Daniel H. Gleason I Mmm:

D. H. CHASON Feb. 20, 1934.

KNEE CONTROL MECHANISM FOR ELECTRIC SEWING MACHINES 3 Sheets-Sheet 3Filed June 25, 1932 3mm Daniel ff. C'izasan wif'neam Patented Feb. 20,1934 UNITED STATES KNEE-CONTROL MECHANISM FOR ELECTRIC SEWING MACHINESDaniel H. Chason, Elizabeth, N. J., assignor to The Singer ManufacturingCompany, Elizabeth, N. J., a corporation of New Jersey Application June25, 1932. Serial No. 619,203

8 Claim.

This invention relates to electric sewing machines of the table orcabinet type adapted to rest upon the floor and has for an object toprovide such a machine with an improved knee-control mechanism forregulating the speed of the sewing machine while in use. A furtherobject of the invention is to provide a knee-control mechanism for anelectric sewing machine, the knee-engaged element of which is shiftableto an inconspicuous or concealed inoperative position and which, when inworking position, follows the movements of the operator's knee with aparallel motion, without rubbing upon or sliding relative to the knee.

With the above and other objects in view, as will hereinafter appear,the invention comprises the devices, combinations and arrangements ofparts hereinafter set forth and illustrated in the accompanying drawingsof a preferred embodiment of the invention, from which the severalfeatures of the invention and the advantages attained thereby will bereadily understood by those skilled in the art.

In the accompanying drawings, Fig. 1 is a frag-'- mentary front sideelevation of a sewing machine table embodying the invention. Fig. 2 is ahorizontal section through one corner of the table, showing theknee-control mechanism in top plan. Fig. 3 is a section on the line 33,Fig. 2, with the woodwork omitted. Fig. 4 is a section substantially onthe line 44, Fig. 2. Fig. 5 is a section on the line 5-5, Fig. 4. Fig; 6is a section on the line 6-6, Fig. 4. vFig. '7 is a disassembledperspective view of one end of the controller-lever and its reinforcingmeans.- Fig. 8 is a section through the reinforced end of thecontroller-lever and Fig. 9 is a disassembled perspective view of theoperating slide-bar and guide elements of the mechanism.

1 represents an electric sewing machine head including the motor 2 andhand-wheel 3 which is installed as usual in a drop-head sewing machinetable or cabinet having a table-top 4, corner legs one of which is shownat 5, a front Wall 6, and end walls one of which is shown at '7. Thedesignation sewing machine table as used herein, has a. broadsignificance and is intended to include a sewing machine support of anyknown cabinet, stand or table type adapted when in use to rest upon thefloor.

, Screwed to the end wall '7 of the table is one leg 8 of an angularsupporting plate the other leg 9 of which is screwed to the front wall 6of the table. Mounted on the leg 8 of the angleplate 8, 9 is amotor-controller-unit or rheostat 10.01 the well knowncarbon-compression type disclosed, for example, in the patent to Chason.No. 1,792,818, of Feb. 1'7, 1931. Such a controllerunit includes anoperating pull-rod or draw-bar 11 carrying the bow-spring bridgingcontactmember 11 which, when pulled downwardly, contacts with andgradually decreases the electrical resistance of the stacks of carbondisks 11 between the terminal screws 12 connected in series with thesewing machine motor, thus increasing the speed of the motor. Therecovery spring 13 raises the draw-bar 11 to its oil position when thedown-pull on such draw-bar is relieved. The lower screw-threaded end ofthe draw-bar 11 carries the adjustable flanged nut 14 which is engagedby the apertured rearward end of a lever 15 fulcrumed on thescrew l6threaded into the supporting-plate-leg 8. A lug 17 on the lever 15enters a notch 17' in the flange of the nut 14 to prevent accidentalturning of the nut 14 when the device is operated. The lever 15 isformed at its forward end with a downturned tip terminating in aninclined lower edge 18 which is reinforced and covered by a U-shapedwear-strip 19 of hardened steel having a rounded bottom edge 19' andheld in place by means of the rivet 20.

Mounted on the angle-plate-leg 9 by screws 21 is the trough-shaped guide22 which slidably receives a slide-bar comprising two sections 23, 24held clamped together by a-thumb-screw 25 which passes freely through aclearance slot 26 in the bottom wall of the guide 22. The thumbscrew 25has a clamping shoulder 27 at the base of the reduced and threaded shank28. The shank 28 passes through a slot 29 in the slidebar section 24 andis screwed into the tapped hole 30 in the slide-bar section 23 whichlatter is in the form of an inverted trough receiving and embracing thesection 24. By loosening the shouldered thumb-screw 25 the section 23may be adjusted endwise of and relative to the section 24 to vary theefiective total length of the slide-bar. F

The slide-bar section 23 is formed at its free end with ahinge-loop 31for the hinge-pin 32 connecting the hinge-loops 33 at the upper end ofthe knee-extension arm 34 which depends from the slide-bar 23, 24 to aposition within reach of the operators knee indicated at 7c. There issecured to the knee-extension arm 34 by means of a screw 35' a stop 35which limits the swinging movement of the arm 34 relative to theslidebar 23, 24 in one direction and determines the operative angularrelation between such arm and slide-bar; the arm 34 making a slightlyacute angle a with the slide-bar 23, 24 when in its operative position,as shown in full lines in Fig. 1. In other words the arm 34 is inclinedaway from a position normal to the slide-bar 23, 24 in the direction inwhich the slide-bar is moved by the operator. Pressure of the operatorsknee exerted laterally in the direction of the arrow, Fig. 1, thereforecauses a slight lifting or upward camming of the arm 34 which tends tobalance any cramping or binding tendency of the slidebar 23, 24 in theguide 22 due to the application of the lateral knee-pressure to the arm34 at a point below the level of the slide-bar.

The slide-bar section 24 is formed at its end remote from the arm 34with upstanding ears 36 which support the bearing pin 37 for the threeanti-friction rollers 38, 39 and 40. The intermediate roller 38 issomewhat smaller in diameter than the outer rollers 39, 40 andoperatively engages the inclined lower edge 19 of the wear-strip 19, asshown in Figs. 3 and 4. The outer rollers 39 and 40 track upon thebottom wall of the guide 22 and an end-piece 41 having a flange 42overhanging the roller 39, as shown in Fig. 3, is secured to the guide22 to resist upward movement of the roller 39 under any twistingtendency of the slide-bar 23, 24 in the guide 22.

The slide-bar 23, 24 is biased in opposition to the force of theoperators knee by means of the spring 43 which is anchored at one end tothe pin '44 on the slide-bar section 24 and at its opposite end to theclip 44' embracing the left-hand end of the guide 22.

A cover-plate 45 protects the spring 43 and has a depending side wall 46which is screwed to one side wall of the guide 22, as shown in Fig. 5.

Projecting upwardly from the bottom wall of the guide 22 is a stop-pin47 which enters the slot 48 in the slide-bar section 24 and limits theendwise movement of the slide-bar in opposite directions. A suitablecover 49 encloses and pro- "tects the controller-unit 10. This cover issecured to the angle-plate-leg 8 by the screw 50.

'It will be observed that the slide-bar 23, 24 and its knee-extension 34move bodily to the right, Fig. 1, from the full line off position to thedotted line extreme on" or full speed position, with a parallel motion,and without sliding relative to or rubbing against the operator's knee.This is an important advantage not heretofore attained in aknee-controller shiftable to an inconspicuous inoperative position; itbeing obvious that the arm 34 may be swung about the hinge pin 32 to ahorizontal concealed position, preferably in line with the slide-b r 23,24, where it is practically hidden beneath the lower edge of the frontwall 6 of the table. Any suitable means may be provided to produceenough friction in the hinge-joint between the bar 24 and arm 34 toretain the arm 34 in any position to which it may be shifted relative tothe bar 24. To this end there may be clamped between the stop 35 and thearm 34 a leaf-spring 35", Fig. 4, which is curved at one end tofrictionally engage or press upon the hinge-loop 31.

The invention is not to be understood as limited to the specificembodiment of the invention shown and described as various modifiedforms of the invention will be apparent to those skilled in the artfromthe teachings of the present disclosure.

Having thus set forth the nature of the invention, what I claim hereinis:

1. The combination with a drop-head sewing machine table adapted in useto rest upon the floor, said table having a table-top and side-wallmembers defining a cavity into which the sewing machine may be droppedwhen not in use, of an electric sewing machine motor-controller mountedin a fixed position within the cavity of said table and including amovable control element, a guide mounted on said table separately fromand independently of said controller at a level above the normalposition of the operators knee, said guide having a guideway disposedsubstantially parallel to the front wall of the table, a slide mountedin said guide and connected to the movable control element of saidcontroller, and a knee-extension depending from said slide to a positionalongside the operator's knee.

2. The combination with a sewing machine table adapted in use to restupon the floor and including a table-top, of an endwise slidable rodmounted below said table-top substantially horizontally at a level abovethe normal position of the operators knee, a knee-extension dependingfrom said slide-rod to a position alongside the operators knee, and anelectric motor-controller connected to be operated by said slide-rod,said knee-extension being operatively related at an 1. acute angle tosaid slide-rod and inclined downwardly away from the operators knee.

3. The combination with a drop-head sewing machine table adapted in useto rest upon the loo floor, said table having a table-top and side-wall6 members defining a cavity into which the sewing machine may be droppedwhen not in use, of an electric sewing machine motor-controller mountedin a fixed position within the cavity of said table and including amovable control element, a guide mounted on said table separately fromand independently of said controller at a level above the normalposition of the operators knee, said guide having a guideway disposedsubstantially parallel to the front wall of the table, a'slide mountedin said guide and connected to the movable control element of saidcontroller, and a knee-extension depending from said slide to a positionalongside the operators knee, said kneeextension being hinged to saidslide to swing upwardly to an inoperative position in a directionopposite the knee-influenced movement thereof.

4. The combination with a sewing machine table having front and endwalls and a straight slideway parallel to said front wall, of adraw-baroperated sewing machine motor-controller unit mounted adjacentthe inner side of said end-wall, a pivoted lever member connected to thedrawbar of the controller-unit, and a knee-operated slide member bodilymovable in said slideway and disposed horizontally at an angle to andterminating adjacent said lever member, one of said members having aninclined portion in operative engagement with the other member.

5. The combination with a supporting angleplate, of a sewing machinemotor-controller unit mounted on one leg of said plate, a leverfulcrumed on said leg of said plate and connected to operate saidcontroller, a knee-operated rod slidably carried by the other leg ofsaid plate, and means for converting endwise sliding movement of saidrod into a rocking movement of said lever.

6. A knee-controller for electric sewing machines comprising asupporting plate adapted for attachment to a sewing machine table, atroughshaped member carried by said supporting plate and constituting aguideway, a slide-bar mounted in said guideway, a knee-extension hingedto said slide-bar, and an electric motor-controller unit connected to beoperated by said slide-bar.

trio

8. An electric sewing machine motor-controller comprising a guideway, aslide-bar received in said guideway and having, at one end three coaxialrollers the outer two of which track upon said guideway, a knee-shiftdepending from said slide-bar, a variable resistance unit, and a movablemember for operating said unit having an inclined edge engaging theintermediate one of said rollers.

DANIEL H. CHASON.

